Mechanism of moisture movement in wood during microwave-vacuum drying

Based on the research of moisture content distribution in Masson pine,the mechanism of moisture transfer through wood dried by microwave-vacuum(MV) was revealed.The results indicated that,during MV drying,moisture distribution in wood was relatively uniform,without an obvious moisture content gradient along the direction of thickness of wood.Moisture distribution in wood was more uniform in the last period of drying.Above Fiber Saturation Point(FSP),the movement of moisture through wood was assumed to be permeable movement of free water and vapor under the action of pressure gradient;below FSP,moisture existing in vapor form in wood moved in response to a pressure gradient.Moisture transfer caused by heat diffusion and a moisture content gradient could be neglected.